A silicon blue/UV selective stripe-shaped photodiode

A novel silicon photodiode for the selective blue/ultraviolet (UV) Light detection is presented. A stripe-shaped anode geometry is used to improve the UV-responsivity of photodiodes fabricated in CMOS processes by minimizing the dead layer area. The selectivity is achieved using a shallow active region, Limited by a high potential barrier at a depth of 450 nm. The measured devices, realized in standard 0.5 mu m CMOS technology, have maximum responsivity at lambda = 400 nm with a quantum efficiency of 53%. A ratio of the responsivities at 400 nm and 1 mu m of 100 is achieved. In comparison to structures with traditional anodes, our stripe-shaped photodiode shows an increase of the UV responsivity by a factor 1.7, as predicted. The special anode geometry also improves the photodiode shunt resistance. (C) 1999 Elsevier Science S.A. All rights reserved.